Existing methods for programming in-flight projectiles have distinct drawbacks. The disadvantage of using the ‘Oerlikon AHEAD’ technique is that it consumes a great deal of power. The programming coils used in this system are bulky and heavy. The use of radio frequency (RF) to transmit the programming signals (‘NAMMO’ radio frequency) is subject to interference from IED suppression technology. BOFORS Larson Patents limited use of this technology to closed bolt designs.
U.S. Patent Pub. No. 2005/0126379 discloses RF data communication link for setting electronic fuzes. Whereas the programming of the projectile is only limited to pre-launch programming. It does not provide any method to program an in-flight projectile.
U.S. Pat. No. 5,102,065 discloses a system to correct the trajectory of a projectile. It transmits corrections signal via a laser beam. The corrections are transmitted to the shell and the shell receives the information and applies it in order to deflect its trajectory. However, the use of self guided shells is very expensive and can only be used for the destruction of even costlier targets. Also U.S. Pat. No. 4,406,430 discloses an optical remote control arrangement for a self guided projectile. The remote control disclosed helps the projectile in hitting its desired target by modifying the trajectory of the projectile. Programming of the projectiles which are not self guided is not discussed in both of the patents.
U.S. Pat. No. 6,216,595 discloses a process for the in-flight programming of the trigger time for a projectile element. The trigger time is transmitted via radio frequency signals. The use of radio frequency adds several disadvantages to effective transmission such as interference from IED suppression technology.
U.S. Pat. No. 6,170,377 discloses a method and apparatus for transmission of programming data to a time fuze of a projectile via an inductive transmission coil. The inductive coils are very bulky and heavy.
U.S. Pat. No. 6,138,547 discloses a method and system for programming fuzes by using electric programming pulses to transmit data between a programmable fuze and a programming device.
In the systems disclosed in the above prior art, due to oscillation of the projectile, it is difficult to maintain consistent contact or proximity between the external source of the programmed pulses and the conductor located on the projectile. Also, both these methods require extensive modification of the weapon design which limits their use.